It is common to use an electric heat trace system in various industrial processes. In the operation of many different types of industrial plants (power generation, pulp and paper, chemical, etc) there exists the need to deploy electric heat trace systems. The purpose of an electric heat trace system is to prevent pipe freeze up when temperatures fall, and/or to maintain process pipe temperature for process efficiencies. If either of these conditions occur (pipe freeze or process media temperature decline), the result can have serious impact upon the ability of the plant to operate at proper efficiency, or to have the plant operate at all. Additionally, once one of these conditions has taken place, it requires immediate attention and significant time from plant personnel to resolve the issue. Since these conditions are always an “upset” and never a “scheduled occurrence”, they normally take personnel away from doing constructive and revenue generating activities. Therefore, when an electric heat trace system fails to keep pipes from freezing or from maintaining a set process temperature, it is always a double loss to the operations of the plant. For one thing the heat trace system failure causes lost revenues from poor or non-existent operations. Furthermore, the heat trace system failure causes lost wages for utilizing plant personnel on non-productive activities.
There are several objectives of a properly functioning electric heat trace system. The real value of a properly functioning electric heat trace system is that it should be acting as “ensurance” against catastrophic failures, maintaining critical process availability, and providing for ease of maintenance and troubleshooting should a problem occur. The benefit to the day-to-day operations is to allow Plant Management the higher value use of their skilled, trained and knowledgeable Technicians. Fixing the problems caused by a frozen pipe, as an example, is NOT the best use of the limited resources (highly trained Technicians) of most industrial plants. And most importantly, whenever an upset occurs, it causes a potential deficiency in the revenue opportunity to the plant. Whether it is a total inability of the plant to operate (i.e. drum level control transmitter at a power plant freezes, creating a “zero” reading thereby not allowing the plant control system to “fire” the boiler) or simply a process temperature not being maintained (i.e. coconut oil component of a chocolate manufacturer being too cold to maintain desired flow rates causing severe delays in the manufacturing cycle), malfunctioning electric heat trace systems can create significant problems and potential losses for industrial plants.
The realities of most industrial plants are not ideal. Even with the potential problems identified to the plant, its personnel, and its profits, the realities of most systems is that the heat trace is often the “last item” on a project and the budget is nearly gone when it is time to specify the proper hardware and installation of the electric heat trace system. This inevitably leads to poor practices in the design and execution of the system, such as multiple circuits per breaker; poorly labeled breaker panel/line list due to changes in field; ineffective design (not enough watts/foot for pipe size; for insulation type and thickness; etc); and little thought given to operating functionality and maintenance concerns.
Electric heat trace systems, even with proper design and specification, can still malfunction once installed in the field. There are several common causes of these malfunctions. One common cause is moisture intrusion from poor installation practices (leaky junction boxes; leaky conduit; leaky insulation barriers; etc), and Insulation problems (poor installation; poor re-installation; environmental moisture). Another common cause is maintenance on operating devices (valves, pumps, etc) that leads to broken or damaged lines.
With the recognition of how important a properly functioning electric heat trace system can be to the operations and profitability of a plant, and with the knowledge that even a properly designed and installed system can develop problems over time, monitoring the “health” of the electric heat trace system is critical.
Control and Monitoring Systems: The objective of an electric heat trace control and monitoring system is simple—to alert plant personnel BEFORE a problem occurs that could cause a catastrophic failure, interrupt critical process availability, or diminish plant revenue generation; and to build in the control logic in order to turn on or turn off specific electric heat trace circuits based upon the input signals received into the control system.
The monitoring systems currently available can be as primitive as a simple LED on the end of an electric heat trace circuit (indication of voltage at the LED), to a sophisticated pipe temperature-sensing and breaker current-sensing multiple circuit system. Most systems fall somewhere in between, with the most common having local visual indication as the primary method of alarm. Although local visual indication is the most common alarming method, it is also the least effective.
No matter the complexity or the simplicity of today's control and monitoring systems, they all suffer from one inherent drawback, and that is that they must all be “hard wired.” Hard wired monitoring systems are permanent “in place” systems and require the same infrastructure and installation issues (electrical code requirements, installation labor, etc) as does any electrical project. These costs are significant when included as part of the original electrical heat trace project, but they grow by a factor of 2× to 3× when a Monitoring System is added after an initial electric heat trace system has been installed. Because of the cost of installation of these monitoring systems (whether as part of the original project, or when considered as an additional “ensurance” measure later), many of the systems get reduced in size and/or capabilities, thus reducing their overall effectiveness, and decreasing their ability to meet the intended objective—to warn personnel BEFORE a problem occurs.
These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of some embodiments of the present invention to provide What is needed is a way to provide a flexible, scalable and low installed cost electric heat trace control and monitoring system that provides the effective and consistent means of alarming.
It is a further object of some embodiments of the invention to provide a heat trace monitoring system that is capable of being manufactured of high quality and at a low cost, enjoys minimum installation costs, provides highly effective function, and which is capable of providing a long and useful life with a minimum of maintenance.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto, it being understood that changes in the precise embodiment of the invention herein disclosed may be made within the scope of what is claimed without departing from the spirit of the invention.